Analytical organic chemistry, biochemistry and medicinal chemistry are faced with a challenge of providing good methods for compounds to be detected in samples of varying origin. Often the compounds appear in complex mixtures from which they must be isolated and the compounds may also be present in very low concentrations. Another complication may be that the sample amounts containing the compounds to be detected can be very small, e.g. blood samples from infants or small children.
Many different methods for separating, isolating, purifying and concentrating bioorganic compounds have been developed over the years. Many are well-known procedures for a person skilled in the art and examples are 2-phase extraction (e.g. aqueous phase-organic phase) and 3-phase extractions (e.g. aqueous phase-organic phase-aqueous phase).
From WO0033050 there are known methods and an apparatus for 2-phase liquid and 3-phase liquid micro extraction for obtaining a high enrichment of an analyte in the acceptor solution. However, the process of classical extraction is based on diffusion of the analyte and this is a slow process. The achievable end concentration of the analyte depends on the equilibrium conditions for each of the phases in e.g. a 2- or 3-phase system, and may result in very low yields, if any.
Even though the above-mentioned processes have been automated, they are still time consuming and often also generate waste of organic solvents.
In order to improve both the selectivity as well as reducing the required time for this type of isolation procedure, the introduction of electromembrane extraction (EME) has favorably added to recent developments in this area.
It is well known that ionized chemical and biochemical substances migrate in solution under the application of an electrical field. This type of transport, which is called electrokinetic migration, is the basis for electrophoresis, and is also widely used for isolation purposes both in industrial applications (purification) and in the field of analytical chemistry (sample preparation).
Frequently, isolation based on electromembrane extraction is carried out in an aqueous one-phase system. One important example of this is electrodialysis, where ionized chemical substances are transferred from an aqueous donor/sample compartment, through the pores of an ion-exchange membrane filled with the same aqueous medium, and into an aqueous acceptor compartment. In electrodialysis, migration selectivity, which is responsible for isolation, is obtained by the presence of small pores in the polymeric membrane, preventing larger molecules from entering the acceptor compartment. Electrodialysis is an important industrial purification and desalting process, and has also been reported as a sample preparation technique in analytical chemistry.
U.S. Pat. No. 8,317,991B2 discloses a method for isolation, purification, concentration and/or enrichment of an organic or biochemical compound through electrokinetic migration i.e. electromembrane extraction (EME). A hollow fiber membrane (HFM) was stated as the most preferred device for the analytical purpose.
U.S. Pat. No. 8,940,146B2 discloses a device for electromembrane extraction, that in one embodiment of the invention utilizes a syringe needle as the second electrode (acceptor phase) together with a hollow fiber membrane.
A remaining problem to be solved with the process described in U.S. Pat. No. 8,317,991B2 is the handling and use of the device as described in said patent. As a first-generation device, there is a large potential for improvements. An improvement (as depicted in U.S. Pat. No. 8,940,146B2) simplified the whole process of electromembrane extraction, also resulting in more reliable results.
There is, however, a need for new processes giving an improved recovery of the required compounds in high purity, and last but not least, there is a need for new technology by which the isolation or purification step proceeds faster and with a high degree of automation.
A remaining challenge was how to facilitate a faster and more automated analysis of organic- or bioorganic compounds in sample solutions.
A further challenge was to improve the electrodes to provide for a faster and more automated analysis.
A further aim of the present disclosure was to provide a solution that could be combined with and used together with existing equipment.
Another aim was to provide for use of commercial automated instruments such as analytic HPLC instruments, or MS instruments such as LC-MS including automated and or robotic auto-samplers utilizing 96-well microplates.